Organic electrochemical transistor

ABSTRACT

A method of making a structure having a patterned a base layer and useful in the fabrication of optical and electronic devices including bioelectronic devices includes, in one embodiment, the steps of: a) providing a layer of a radiation-sensitive resin; b) exposing the layer of radiation-sensitive resin to patterned radiation to form a base layer precursor having a first pattern of exposed radiation-sensitive resin and a second pattern of unexposed radiation-sensitive resin; c) providing a layer of fluoropolymer in a third pattern over the base layer precursor to form a first intermediate structure; d) treating the first intermediate structure to form a second intermediate structure; and e) selectively removing either the first or second pattern of resin by contacting the second intermediate structure with a resin developing agent, thereby forming the patterned base layer. The method is capable of providing multilayer articles having almost any shape at high resolution without the need for expensive or damaging mechanical or laser cutting.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 14/547,735, which claims the benefit of U.S. ProvisionalApplication No. 61/906,155, filed Nov. 19, 2013, and which applicationsare incorporated herein by reference. A claim of priority is made toeach of the above disclosed applications.

BACKGROUND

The present disclosure relates to method of making a structure having apatterned a base layer. The method is particularly useful in thefabrication of optical and electronic devices including bioelectronicdevices.

There are many methods available for patterning multi-layer structures,e.g., in the formation of electronic, optical or mechanical componentsand devices. The particular method chosen depends on many factors suchas dimensional tolerances, material compatibilities, throughputrequirements, manufacturing costs and the like. Photolithography is acommon patterning technique, used especially in the construction ofmicroelectronic devices on flat surfaces such as glass, silicon wafersor plastic. Photolithography can provide high resolution images and maybe done on a large scale. For example, electronic back planes fordisplays are commonly constructed using photolithography. Flat surfaceshelp enable uniform coating of various layers and high qualityphotolithographic processes. In manufacturing, a plurality of backplanesor semiconductor chips are typically constructed on a flat sheet orwafer of glass or silicon and then laser- or mechanically diced intoindividual backplanes or chips. This can generate unwanted dust anddebris that may contaminate the devices and result in additional washingsteps.

Sometimes multilayer structures or devices do not have a symmetricalshape and they are not easily cut into the desired shape withoutdamaging the structure or causing low yield. One can optionally cut asupport into the desired shape first and then apply additional layers,but at the sacrifice of the economy of scale. Further, coating uniformlayers and photopatterning is often not amenable to non-symmetricallyshaped articles.

Thus, a need exists for an improved method for patterning multilayerstructures. In particular, a method of patterning structures is neededthat is capable of providing articles having shapes other than simplesquares or parallelograms, with high precision and large throughput, butwithout the need for laser or mechanical dicing.

SUMMARY

In accordance with the present disclosure, a method of making astructure having a patterned base layer comprises: providing a layer ofa radiation-sensitive resin; exposing the layer of radiation-sensitiveresin to patterned radiation to form a base layer precursor having afirst pattern of exposed radiation-sensitive resin and a second patternof unexposed radiation-sensitive resin; providing a layer offluoropolymer in a third pattern over the base layer precursor to form afirst intermediate structure; treating the first intermediate structureto form a second intermediate structure; and selectively removing eitherthe first or second pattern of resin by contacting the secondintermediate structure with a resin developing agent, thereby formingthe patterned base layer.

In an embodiment, the present disclosure is capable of providingarticles having shapes other than simple squares or parallelograms, withhigh precision and large throughput, but without the need for mechanicaldicing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow chart depicting the steps in an embodiment of thepresent disclosure;

FIG. 2 is a cross-sectional view depicting a layer ofradiation-sensitive resin according to an embodiment of the presentdisclosure;

FIG. 3 is a cross-sectional view depicting the formation of base layerprecursor according to an embodiment of the present disclosure;

FIG. 4A-4C is a series of cross-sectional views depicting various stagesin the formation of a first intermediate structure according to anembodiment of the present disclosure;

FIG. 5A-5D is a series of cross-sectional views depicting various stagesin the formation of a first intermediate structure according to anotherembodiment of the present disclosure;

FIG. 6A-6B is a series of cross-sectional views depicting various stagesin the formation of a second intermediate structure according to anembodiment of the present disclosure;

FIG. 7 is a cross-sectional view of a patterned base layer and apatterned base layer structure according to an embodiment of the presentdisclosure;

FIG. 8 is a cross-sectional view of a patterned base layer structureremoved from an optional carrier substrate according to an embodiment ofthe present disclosure;

FIG. 9A-9C is a series of cross-sectional views depicting various stagesin the formation of a patterned base layer structure according toanother embodiment of the present disclosure;

FIG. 10 is a plan view of a carrier substrate having a release layer andtwo patterned base layer structures provided over the carrier substrateaccording to an embodiment of the present disclosure;

FIG. 11 is a cross-sectional view taken along cut line A-A drawn in FIG.10;

FIG. 12A-12B is a series of cross-sectional views depicting variousstages in the formation of a secondary substrate structure according toan embodiment of the present disclosure;

FIG. 13 is a plan view of a patterned base layer structure arrayaccording to an embodiment of the present disclosure;

FIG. 14 is a plan view showing the tip of a shank portion of a patternedbase layer structure according to an embodiment of the presentdisclosure;

FIG. 15 is a plan view showing a shank portion tip according to anotherembodiment of the present disclosure;

FIG. 16 is a cross-sectional view taken along cut line C-C drawn in FIG.15;

FIG. 17 is a cross-sectional view of a shank portion tip according to anembodiment of the present disclosure that further includes a modifyingmaterial;

FIG. 18A-18B is a series of cross-sectional views depicting variousstages in the formation of a patterned base layer structure according toan embodiment of the present disclosure that further includes aprotective fluoropolymer layer;

FIG. 19A-19E is a series of cross-sectional views depicting variousstages in the formation of a patterned base layer structure according toan embodiment of the present disclosure;

FIG. 20A-20B are plan views showing a OECT device provided on a shankportion tip according to an embodiment of the present disclosure;

FIG. 20C is a cross-sectional view taken along cut line D-D drawn inFIG. 20A; and

FIG. 21 is a plan view depicting different areas (quadrants) of a squaresilicon chip.

DETAILED DESCRIPTION

It is to be understood that the attached drawings are for purposes ofillustrating the concepts of the disclosure and may not be to scale.

A flow diagram for an embodiment of the present disclosure is shown inFIG. 1, and includes the step 2 of providing a layer ofradiation-sensitive resin, the step 4 of forming a base layer precursor,the step 6 of forming a first intermediate structure, the step 8 offorming a second intermediate structure, and the step 9 of forming apatterned base layer by contacting the second intermediate structurewith a resin developing agent. Each step is discussed in more detail,below.

Turning to an embodiment shown in FIG. 2, a layer of radiation-sensitiveresin 20 is provided over an optional carrier substrate 22 along with anoptional intervening release layer 24. The layer of radiation-sensitiveresin 20 may include any suitable material that can be selectivelyexposed to appropriate radiation to form exposed and unexposed areashaving differential solubility in a resin developing agent. There is noparticular limitation on the choice of radiation-sensitive material andsuch choice will depend largely upon its intended function in apatterned structure. The radiation-sensitive resin material can beprimarily inorganic in nature (e.g., an imagable sol-gel), primarilyorganic (e.g., a photosensitive polymer) or a hybrid (e.g., a siloxanepolymer). Some non-limiting examples of radiation-sensitive resinsinclude epoxy-based photopolymers (such as SU8), phenol-formaldehydephotoresists (such as Novolac), photo polymerizable resins,photo-cross-linking resins (e.g., resins having vinyl groups such asstyrenes, cinnamates and acrylates), and polymeric materials that can bemodified as known in the art to impart photosensitivity (such as PDMS,silicones, polyimides, polystyrenes). The radiation-sensitive resin mayoptionally be bio-resorbable, e.g., based on a photosensitizedpolyethylene glycol (such as PEG diacrylate), polylactic acid,polyglycolic acid, polyvinylalcohol, polyacrylic acid, polycaprolactone,collagen, polyester-ether, a polyamino acid or a combination thereof. Inan embodiment, the radiation-sensitive resin is selected to have lowsolubility in fluorinated solvents that may be used in subsequent steps.In an embodiment, the radiation-sensitive resin has a fluorine contentby weight of less than 30%, preferably less than 15%. In an embodiment,the radiation-sensitive resin has a fluorine content of less than 1% byweight.

The layer of radiation-sensitive resin 20 may be provided as a preformedsheet or coated from as solution, e.g., by spin coating, curtaincoating, doctor-blade coating, dip coating, ink jet coating, sprayapplication or the like. The radiation-sensitive resin can be positivetone or negative tone. A positive tone resin is one where exposed areasare more soluble in the resin developing agent than unexposed areas. Anegative tone resin is one where exposed areas are less soluble in theresin developing agent than unexposed areas. There is no particularlimitation on the thickness of the layer of radiation-sensitive resin,other than it cannot be so thick that it will not properly image andthat the final thickness will serve its intended purpose. In anembodiment, the layer of radiation-sensitive resin may have a thicknessin a range of 0.5 to 1000 μm, or in another embodiment, a range of 10 to100 μm, or in another embodiment, a range of 20 to 60 μm, or in anotherembodiment in a range of 0.5 to 10 μm.

The optional carrier substrate 22 is particularly useful when coatingthe radiation-sensitive resin from a solution. Such substrates arepreferably flat and may be formed from sheets or wafers of glass,silicon, metal, ceramic, plastic or combinations thereof. The optionalrelease layer 24 can be useful when one desires to separate a structurehaving a patterned base layer (see below) from a carrier substrate. Therelease layer may be a thin layer that simply lowers adhesion betweenlayers (e.g., a layer of surfactant) or it may be a layer that hasreasonable adhesion at first, but can be activated in some way, e.g., bythermal or light activation, to promote release when desired. Suchmaterials are known in the art and some are used, e.g., as“light-to-heat conversion” layers or “transfer assist” layers in thermaland laser transfer from donor sheets to receivers. Some non-limitingexamples of light-to-heat conversion layers can be found in WO2008/010982, which is incorporated by reference herein.

The radiation used to expose the radiation-sensitive resin depends uponthe resin. In an embodiment, the radiation may be relatively low energysuch as infra-red, e.g., provided by a lamp, a laser or a heatingelement. In an embodiment, the radiation may be high energy such asX-ray or e-beam. In an embodiment, the radiation is visible orultraviolet light. In a preferred embodiment, the radiation is in awavelength range of 300 nm to 450 nm. Patterned visible or UV light maybe provided across the layer of radiation-sensitive resin by, e.g.,using a photomask in conjunction with a radiation source such as amercury lamp, using a projection device that may optionally step andrepeat across the resin, rastering a laser, scanning a series of LEDs orproviding a digital matrix array of light-emitting elements in closeproximity to the layer, or applying any other suitable method known inthe art.

Turning to an embodiment shown in FIG. 3, a photomask 45 is providedbetween a radiation source that emits radiation 46 (e.g., “i-line” UVlight at 365 nm) and the layer of radiation sensitive resin 20 (e.g.,resin that is sensitive to 365 nm radiation), thereby forming a baselayer precursor 40 having a first pattern 41 of exposedradiation-sensitive resin and a second pattern 42 of unexposedradiation-sensitive resin. In this embodiment, the radiation-sensitiveresin is negative tone. For example, the patterned radiation causescross-linking or polymerization in the first pattern of exposedradiation-sensitive resin making it less soluble in the resin developingagent. In some embodiments, the base layer precursor may need asecondary activation step such as a baking step, commonly referred to asa “post exposure bake” or “PEB”. When that is the case, the PEB may beperformed before other process steps, but in another embodiment, it maybe done later in the process (but before contact with a resin developingagent). A feature of the present disclosure is that the base layerprecursor undergoes further processing steps (patterning steps inparticular, as detailed below) prior to contact with a resin developingagent, whereas in the prior art, a photosensitive resin is normallyexposed and developed in sequence without any significant interveningprocess steps. Thus, the further processing steps are performed over abase layer precursor that is relatively flat, which may be advantageous.In an embodiment, thickness variations across the base layer precursorare within 50% of the average thickness, preferably less than 15% ormore preferably less than 5%. In an embodiment, the thickness variationsacross a base layer precursor are less than 25 μm, preferably less than8 μm and more preferably less than 2 μm. In an embodiment, the baselayer precursor is selected to have low solubility in fluorinatedsolvents that may be used in subsequent steps.

A first intermediate structure is formed by providing a patterned layerof a fluoropolymer over the base layer precursors. By not firstdeveloping the base layer precursor, the surface is still generallyflat, which enables many methods of applying or forming a patternedfluoropolymer. Some non-limiting examples include ink jet depositing aliquid containing a fluoropolymer, patterned thermal transfer of a dryfluoropolymer from a donor sheet, and flexographic printing of a liquidcontaining a fluoropolymer. In a preferred embodiment, the layer ofpatterned fluoropolymer is provided by coating a solution comprising afluorinated solvent and a fluoropolymer and applying photolithographicmethods, e.g., as disclosed in U.S. patent application publications2011/0159252 and 2010/0289019, the entire contents of which areincorporated by reference. The generally flat base layer precursorsimplifies coating and photolithography. In an embodiment, anintervening layer of another material may be provided between thepatterned layer of fluoropolymer and the base layer precursor. Suchother optional material layer and method of application should beselected so that is compatible with the base layer precursor (e.g.,parylene). In a preferred embodiment, the fluoropolymer is provided indirect contact with the base layer precursor from a solution comprisinga fluorinated solvent. It is often the case that either the exposed orunexposed areas of a radiation-sensitive resin are easily dissolved orotherwise altered by common organic solvents or aqueous media. This isthe basis for how such photo-patternable resins work. Since the baselayer precursor has both, this significantly limits the choice of layersone can apply directly on the base layer. It has been found thatfluorinated solvents have been generally found to be “orthogonal” insolubility relative to both exposed and unexposed photosensitive resins,i.e., neither are easily dissolved into fluorinated solvents such asthose described below. Thus, application of a patterned fluoropolymerusing fluorinated solvents is particularly versatile.

FIGS. 4A-4C illustrate an embodiment for forming a first intermediatestructure 67 using a photosensitive fluoropolymer. In FIG. 4A, a layerof photosensitive fluoropolymer 60 is formed by applying over the baselayer precursor a composition comprising a photosensitive fluoropolymermaterial and a first fluorinated solvent, e.g., a hydrofluoroethersolvent. The layer of photosensitive fluoropolymer 60 may include anysuitable fluorinated material that can be selectively exposed toappropriate radiation to form exposed and unexposed areas havingdifferential solubility in a fluoropolymer developing solution. Thephotosensitive fluoropolymer can be negative tone or positive tone, andas described below, there are numerous options for its chemicalcomposition and image development. The photosensitive fluoropolymer 60preferably has a different spectral sensitivity than theradiation-sensitive resin so that exposure of the photosensitivefluoropolymer does not cause unwanted exposure of theradiation-sensitive resin. In an alternative embodiment, thephotosensitive fluoropolymer substantially absorbs enough radiation toprevent problematic exposure of the radiation-sensitive resin. In analternative embodiment an intervening layer containing a light absorbingcompound is provided between the base layer precursor and thephotosensitive fluoropolymer. Alternatively, the photosensitive resincould be selected as one that requires, and is given, a PEB prior toapplication of the photosensitive fluoropolymer, and the selectedfluoropolymer needs no PEB or PEB conditions that will not affect theunderlying photosensitive resin. In the illustrated embodiment, thephotosensitive fluoropolymer is negative tone and developable in asolution (a fluoropolymer developing agent) comprising one or morefluorinated solvents, e.g., a hydrofluoroether. Unless otherwise noted,the term “solution” is used broadly herein to mean any flowablematerial. Examples of “solutions” include, but are not limited to:single solvent liquids; homogeneous mixtures of a solvent with one ormore other solvents, with one or more solutes, and combinations thereof;and heterogeneous or multi-phase mixtures such as emulsions, dispersionsand the like.

Referring now to FIG. 4B, a photomask 62 is provided between radiationsource emitting radiation 61 (e.g., “g-line” UV light at 436 nm) and thelayer of photosensitive fluoropolymer (e.g., that is sensitive to 436 nmradiation), thereby forming an exposed layer of photosensitivefluoropolymer 63 having a pattern 64 of exposed photosensitivefluoropolymer and a pattern 65 of unexposed photosensitivefluoropolymer. In FIG. 4C, the exposed layer of photosensitivefluoropolymer 63 is then contacted with a photosensitive fluoropolymerdeveloping agent, preferably having at least 50% by volume of a secondfluorinated solvent (that may the same as or different from the firstfluorinated solvent), to selectively remove unexposed areas of thephotosensitive fluoropolymer thereby forming a layer of fluoropolymer ina third pattern 66 and first intermediate structure 67. Contacting canbe accomplished by immersion into the developing agent or by coating thestructure with the developing solution in some way, e.g., by spincoating or spray coating. The contacting can be performed multiple timesif necessary.

The pattern 64 of exposed photosensitive fluoropolymer corresponds tothe third pattern 66, but is not necessarily identical to it. Pattern 64might be slightly larger or smaller than pattern 66 but will havegenerally the same shape. A difference may be caused, e.g., bynon-uniformity at exposure edges, diffusion of activated photo-acidgenerator groups and development kinetics, in addition to many otherpotential sources. Although drawn as vertical, the sidewalls of thelayer of fluoropolymer in a third pattern 66 may have some other shapeafter development. Rather than rectangular, its cross section couldresemble a trapezoid, an inverted trapezoid (undercut), or some othershape, e.g., one having curved sidewalls.

In an alternative embodiment shown in FIGS. 5A-5D, photolithographicpatterning is applied to a bilayer structure. In an embodiment shown inFIG. 5A, a layer of an initially non-patterned fluoropolymer 160 isapplied over the base layer precursor, e.g., by coating from a solutionor by dry film transfer from a donor sheet. In this embodiment, thefluoropolymer is soluble in one or more fluorinated solvents that do notinteract significantly with the base layer precursor. Next, a layer of aphotosensitive second polymer 161 (e.g., a photoresist) is provided overthe non-patterned fluoropolymer 160 to form an unpatterned bilayerstructure. The photosensitive second polymer 161 may, for example, becoated from an organic or aqueous solution in which the underlyingnon-patterned fluoropolymer is not soluble. The photosensitive secondpolymer 161 may be a photosensitive fluoropolymer coated from afluorinated solvent that does not significantly dissolve or impact theunderlying non-patterned fluoropolymer 160. The photosensitive secondpolymer 161 may alternatively be any conventional photoresist orphotopolymer that can be coated and developed using aqueous ornon-fluorinated organic solvents that do not deleteriously interact withthe underlying fluoropolymer layer. The developed photosensitive secondpolymer should also have low solubility in fluorinated solvents used topattern the underlying fluoropolymer layer (see below). In anembodiment, the photosensitive second polymer has a total fluorinecontent by weight of less than 30%, alternatively less than 15%. In anembodiment, the photosensitive second polymer has a total fluorinecontent of less that 1% by weight.

Referring now to FIG. 5B, a photomask 62 is provided between radiationsource emitting radiation 61 (e.g., “g-line” UV light at 436 nm) and thelayer of photosensitive second polymer (e.g., that is sensitive to 436nm radiation), thereby forming an exposed layer of photosensitive secondpolymer 163 having a pattern 164 of exposed photosensitive secondpolymer and a pattern 165 of unexposed photosensitive second polymer. InFIG. 5C, the exposed layer of photosensitive second polymer 163 is thencontacted with a second polymer developing agent to selectively removeunexposed areas of the photosensitive second polymer thereby forming apartially patterned bilayer structure 168 including a patterned layer166 of second polymer corresponding to a third pattern provided over thenon-patterned fluoropolymer layer 160. The non-patterned fluoropolymer160 is not highly soluble in the second polymer developing agent and isnot removed at this point. In an alternative embodiment, the patternedlayer 166 of second polymer may be formed by printing.

The partially patterned bilayer structure 168 is contacted with afluorinated solvent in which the fluoropolymer has some solubility, butnot the second polymer. As shown in FIG. 5D, this results in selectiveremoval of the fluoropolymer in areas not covered by the second polymer,thereby forming a layer of fluoropolymer in a third pattern 66 and firstintermediate structure 167. It should be noted that the solubility ofthe fluoropolymer in the fluorinated solvent may lead to some harmlessundercutting (not shown), but this can be controlled through selectionof time, temperature, choice of fluorinated solvents, agitation and thelike. In some embodiments, the undercutting is desirable. If thecontacting with the fluorinated solvent is done under conditions tooaggressive, this may result in lift-off of the second polymer. This isnot desired at this point, but may be desirable later on if patterningadditional material layers.

The first intermediate structure is next treated to form a secondintermediate structure. Herein, the term “treated” means that the firstintermediate structure is acted upon by at least two subsequent processsteps, not including any optional heating steps. These process steps canbe chemical or physical in nature. For example, the treatment mayinclude deposition of one or more additional material layers in apattern. Alternatively, or in combination, the treatment may involveetching or modifying the surface of a material layer not covered by thethird pattern of fluoropolymer, e.g., the base layer precursor or anintervening layer between the fluoropolymer and the third pattern. Thetreatment may involve the formation of a multilayer structure over thebase layer precursor, which might involve many steps more than just two.

FIGS. 6A and 6B illustrate an embodiment wherein the treatment forms apatterned layer. In FIG. 6A, a material layer 80 is deposited over thefirst intermediate structure (from FIG. 4C) as a first step. Thematerial can, for example, be coated in some way from a liquid ordeposited from vacuum or vapor phase (sputtering, evaporation and thelike). Multiple layers of different materials can optionally bedeposited. There is no particular limitation on the choice of material,which will depend on the desired function. In the present embodiment,material layer 80 is a bilayer structure including an adhesion promotingmaterial such as titanium and a thicker electrically conductive materialsuch as gold. As shown in FIG. 6B, the structure is then contacted witha stripping solution capable of dissolving the third pattern offluoropolymer, thereby lifting off the overlying material layer 80 andforming the second intermediate structure 82 having a patterned materiallayer 81. In the present embodiment, material layer 81 may be aconductive electrode.

The first pattern of exposed radiation-sensitive resin may have a firstglass transition temperature (Tg) and the second pattern of unexposedradiation-sensitive resin may have a second Tg that is the same as ordifferent from the first Tg. In an embodiment, the steps of forming thefirst and second intermediate structures do not subject the base layerprecursor to temperatures that exceed the first Tg, and preferably,either the first Tg or the second Tg. In an embodiment, during theprocessing steps used to make the first and second intermediatestructures, the temperature of the base layer precursor does not exceed100° C., preferably 65° C. and more preferably 50° C. In somesituations, it has been found that exposure to high temperatures maycause buckling or deformations in the base layer precursor. This is onereason that, if a secondary activation bake step (post exposure bake) isrequired on the base layer precursor as discussed above, this bakingstep is preferably done before further processing, as such dimensionalchanges in the base layer precursor will have less impact if they occurinitially, before the formation of the first and second intermediatestructures.

A patterned base layer is formed by contacting the second intermediatestructure with a resin developing solution to remove either the firstpattern of exposed radiation-sensitive resin or the second pattern ofunexposed radiation-sensitive resin, depending on whether the resinmaterial is positive or negative tone. In an embodiment illustrated inFIG. 7, the radiation-sensitive resin is negative tone and contact withthe resin developing solution selectively removes second pattern 42 ofunexposed radiation-sensitive resin, thereby forming patterned baselayer 90. Contacting can be accomplished by immersion into the resindeveloping solution or by coating the structure with the resindeveloping solution in some way, e.g., by spin coating or spray coating.The contacting can be performed multiple times if necessary. Althoughdrawn as vertical, the sidewalls of the patterned base layer 90 may havesome other shape after development. Rather than rectangular, its crosssection could resemble a trapezoid, an inverted trapezoid (undercut), orsome other shape, e.g., one having curved sidewalls.

FIGS. 19A-19E illustrate another embodiment wherein treatment forms apatterned layer by using an etch method. In FIG. 19A a material layer280 is deposited over the base layer precursor (from FIG. 4C). Thematerial can, for example, be coated in some way from or as a liquid ordeposited from vacuum or vapor phase (sputtering, evaporation and thelike). If coated from a solvent or solution, it should be chosen not tohave deleterious effects on the underlying base layer precursor.Multiple layers of different materials can optionally be deposited.Depending upon the optical properties of the material layer 280, it mayoptionally be deposited prior to exposure and optional post-exposurebaking of the radiation sensitive resin. There is no particularlimitation on the choice of material, which will depend on the desiredfunction. In the present embodiment, material layer 280 is an organicsemiconductor.

Referring to FIGS. 19A-19C, and in a manner analogous to that describedwith respect to FIGS. 4A-4C, a first intermediate structure 267 ifformed by photopatterning a layer of photosensitive fluoropolymer 260(provided over the material layer 280) using radiation source 261 andphotomask 262 to form an exposed layer of photosensitive fluoropolymer263 having a pattern 264 of exposed photosensitive fluoropolymer and apattern 265 of unexposed photosensitive fluoropolymer. Following anoptional post exposure bake, the exposed layer of photosensitivefluoropolymer 263 is contacted with a fluoropolymer developing agent toremove (in this embodiment) unexposed areas of photosensitivefluoropolymer thereby forming a layer of fluoropolymer in a thirdpattern 266 and the first intermediate structure 267.

FIG. 19D, the first intermediate structure 267 is treated by etching thematerial layer 280 that is not covered by the third pattern 266 offluoropolymer, thereby forming patterned material layer 281 and secondintermediate structure 282. Etching may be accomplished, for example bydry etching (e.g. by oxygen plasma) or wet etching (e.g., by using asolvent in which the material layer will dissolve or disperse into).

In FIG. 19E, a patterned base layer 290 and patterned base layerstructure 291 are formed by development of the unexposed portions of thephotosensitive resin. In the embodiment shown, the third pattern offluoropolymer 266 has been removed, e.g., by contact with a fluorinatedstripping agent. In an embodiment, the third pattern of fluoropolymer266 is removed after development of the photosensitive resin. In anembodiment, etching of the material layer and development of thephotosensitive resin is done in a common step prior to removal of thethird pattern of fluoropolymer 266. In an alternative embodiment, thethird pattern of fluoropolymer 266 is removed prior to development ofthe photosensitive resin. In another embodiment, the third pattern offluoropolymer 266 is not removed at remains as part of the patternedbase layer structure.

In an embodiment, the thickness of the patterned base layer is greaterthan the thickness of the patterned material layer. In an embodiment,the patterned base layer may have a Young's modulus of greater than 1kPa, or when higher mechanical strength is required, greater than 0.01GPa, or alternatively greater than 0.1 GPa, or alternatively greaterthan 1 GPa, depending on the physical requirements of its intendedpurpose. In an embodiment, the patterned base layer has a Tg of 100° C.or greater. For example, a patterned base layer made from an epoxy-crosslinked photosensitive resin such as SU8 has been reported to have a Tgof about 200° C.

The patterned base layer 90 (or 290), along with layers and featuresformed over the patterned base layer, collectively, the patterned baselayer structure 91 (or 291), may optionally be removed from the carriersubstrate 22 as shown in FIG. 8. Non-limiting methods of such removalinclude physical peeling or pulling of the patterned base layerstructure off of the carrier substrate, heating or cooling to causedifferential expansion/contraction between patterned base layerstructure and carrier substrate thereby causing separation, dissolvingthe release layer 24, or activating the release layer by light or heatto cause separation. A tool having an adhesive layer or grippingcapability (mechanical, suction, magnetic or other means) may be appliedto the top portion of the patterned base layer structure to aid in suchremoval. In an embodiment, the resin developing agent also dissolves therelease layer 24 or otherwise causes release from the carrier substrate.

In an alternative embodiment shown in FIGS. 9A-9C, a second intermediatestructure is first removed from the optional carrier substrate and thencontacted with a resin developing agent. For example, a secondintermediate structure 83 may be formed as described previously, buthaving a slightly different structure including areas of unexposed resin42 directly beneath the patterned material layer 81 (FIG. 9A). Next, thesecond intermediate structure 83 is removed from the carrier substrateand release layer (FIG. 9B). Then, a second intermediate structure iscontacted with a resin developing solution to form patterned base layer92 and patterned base layer structure 93 (FIG. 9C). This alternativeembodiment permits resin developing solution to reach unexposed resinareas that might not be otherwise accessible when the carrier substrateis still in place. The patterned material layer 81 may, for example,function as a membrane and have (from a top view, not shown) a circularstructure supported at its edge by the patterned base layer.

There is no particular limitation on the shape of the patterned baselayer. The shape may be symmetrical or asymmetrical, be simple orcomplex, have round or straight edges (or both) and the like. It dependsupon the intended function of the base layer structure. The resolutionof the shape is determined mainly by the sensitivity ofradiation-sensitive resin material, the resolution of patternedradiation and the development kinetics when the base layer precursor iscontacted with resin developing agent.

Multiple, separate base layer structures may be formed using the methodsof the present disclosure. These individual base layer structures may beall identical in sizes and shapes, or some or all may be different.There is no particular limitation on the number of base layer structuresthat may be formed. In an embodiment, FIG. 10 shows a plan view of acarrier substrate having provided thereon a release layer 24 and twodifferent patterned base layer structures formed over the release layer.A first patterned base layer structure 91 a includes patterned baselayer 90 a and patterned material layer 81 a. A second patterned baselayer structure 91 b includes patterned base layer 90 b and patternedmaterial layer 81 b. The shapes and sizes of the two structures aredifferent. This is further illustrated in FIG. 11 as a cross-sectionalview taken along cut line A-A drawn in FIG. 10. In another embodiment,the patterned material layer 81 a may comprise a different material thanthat of patterned material layer 81 b. For example, the steps shown inFIGS. 4A-C and FIGS. 6A-B can be performed multiple times usingdifferent patterns and material layers. The first time can be used topattern material layer 81 a. The second time can be used to patternmaterial layer 81 b. After both patterned material layers 81 a and 81 bhave been formed (forming a second intermediate structure), the secondintermediate structure can be contacted with a resin developing solutionas previously described.

In an embodiment, one or more patterned base layer structures can betransferred to a second substrate. FIG. 12A illustrates an embodimentwherein both the first and second patterned base layer structures (91 aand 91 b, respectively) described in FIGS. 10 and 11 are transferred tosecondary substrate 200. In this embodiment, the carrier substrate 22acts as a donor sheet. There is no particular limitation on thesecondary substrate 200 in this embodiment other than it be capable ofreceiving the patterned base layer structures. Secondary substrate 200may optionally be a simple or complex multilayer structure, e.g., anelectrical backplane. As shown in this embodiment, secondary substrate200 may have an adhesion promoting layer 201 applied or patterned overthe top to aid in the transfer of the first and second patterned baselayer structures. An adhesion promoting layer may further serve anotherfunction, e.g., it can be a refractive index matching layer, ananisotropic conductor, a charge transport layer or the like. Uponapplication of pressure 210 and optionally heat or light (e.g. toactivate release layer 24) or some other stimulus, adhesion betweenpatterned base layer structures to the substrate or adhesion promotinglayer exceeds the adhesion to the carrier substrate and the structuresare transferred to the secondary substrate 200 as shown in FIG. 12B,thereby forming secondary substrate structure 220 wherein the patternedmaterial layers face inwardly toward the secondary substrate.

In another embodiment, the patterned base layer structures aretransferred to secondary substrate comprising a bioresorbable materialfor use in a bioelectronic or other biomedical device, e.g., an in vivobioelectronic sensor.

In another embodiment, the one or more patterned base layer structurescan be transferred to a second substrate by a “pick and place”operation. In pick and place, the patterned base layer structure islifted (picked) off the carrier substrate by an intermediate mechanicalassembly that can appropriately grip the structure, e.g., by physicalcoupling, through an adhesive layer, via magnetic means or the like. Theintermediate mechanical assembly may optionally be a robotic devicehaving an arm portion and a gripping portion. The intermediatemechanical assembly is subsequently positioned to allow placement of thepatterned base layer structure onto a secondary substrate as desired. Inthis embodiment the patterned material layers face outwardly away fromthe secondary substrate.

In another embodiment, the one or more patterned base layer structuresare released from a carrier substrate into an inert fluid, and thestructures are transferred to a second substrate by fluidicself-assembly. In an embodiment, the second substrate has recessedfeatures that uniquely match a particular base layer structure. Forexample, a secondary substrate may have a circular recess capable ofselectively receiving a patterned base layer structure such as 91 a anda rectangular recess capable of selectively receiving a patterned baselayer structure such as 91 b from a fluidic stream containing both typesof patterned base layer structures.

The method according to the present disclosure can be used to fabricatedevices such as electronic (including bioelectronic), optical, medicaland mechanical (including MEMS) devices. In an embodiment, the patternedbase layer structure includes an electronic or optical feature formedover the patterned base layer. For example, the feature may be providedby a patterned material layer. In some non-limiting examples, thefeature may form a portion (or all) of a transistor, a capacitor, alight-emitting device, a touch screen, a photovoltaic device, a displaydevice, a chemical sensor, a pressure sensor, a light sensor, abiosensor, a bio-stimulator, a bioelectronic ion pump, an organicelectrochemical transistor, an electrochemical cell, a light guide, alens, a reflector, a color filter, a microelectromechanical structure, apiezoelectric device or combinations thereof.

As an example embodiment, FIG. 13 shows a plan view of a patterned baselayer structure array 300. The array includes four patterned base layerstructures, 391 a, 391 b, 391 c, and 391 d, provided over release layer324 and a carrier substrate (not visible in this view). Each patternedbase layer structure has a corresponding patterned base layer 390(illustrated as 390 a for base layer structure 391 a) made, e.g., fromSU8. Each of the patterned base layer structures in this embodimentforms a probe that may be used as bioelectronic device such as abiosensor or bio-stimulator. Each patterned base layer structure has anelectrical contact portion 395 (illustrated as 395 a for patterned baselayer structure 391 a) and a shank portion 398 (illustrated as 398 a forpatterned base layer structure 391 a). The electrical contact portion395 includes electrical contact pads 381 (illustrated as 381 a forpatterned base layer structure 391 a) that provide connection toelectronic driving circuitry (not shown). Conductive traces 382(illustrated as 382 a for patterned base layer structure 391 a) provideelectrical connection from the electrical contact pads 381 to electrodepads near the far tip of the shank. The electrode pads are very small inthis embodiment and are not shown in FIG. 13. The shank portion 398 ofthe patterned base layer structure may optionally be designed to havesufficient mechanical strength to allow insertion into biologicaltissue, for example, the base layer structures in this embodiment areapproximately 50 μm in thickness.

The tip of shank portion 398 for patterned base layer structure 391 a ishighlighted by circle B in FIG. 13 and a magnified plan view is shown inFIG. 14 (excluding the release layer 24 for clarity). Five electrodepads 383 a are provided near the pointed tip of the shank and each areindividually electrically connected to conductive traces 382 a that leadback to electrical contact pads 381 a shown in FIG. 13.

The structures shown in FIGS. 13-14 can readily be produced using themethods disclosed above. Patterned contact pads 381, conductive traces382 and electrode pads 383 are formed prior to contacting with a resindeveloping solution, e.g., using gold as the patterned material layerand a lift-off patterning process in conjunction with a negative tone,photosensitive fluoropolymer as discussed previously. In an embodiment,the photosensitive fluoropolymer used in the lift-off process is onehaving a carboxylic acid-forming precursor group or an alcohol-formingprecursor group, or both, and development and stripping of thephotosensitive fluoropolymer is done using two different fluorinatedsolvents.

The shank portion of the probe may optionally be inserted intobiological tissue and each electrode pad may be electronically addressedto serve some function. In some non-limiting examples, an electrode padmay serve to inject charge into the tissue (bio-stimulator), it mayserve to read out electrical impulses (bio-sensor), and it may be usedto measure temperature. Each probe in this embodiment has five electrodepads, so each electrode pad may optionally serve different functions.

In some cases, it may be advantageous to insulate the conductive tracesso that only the electrode pads are in electrical contact to the desiredtarget, e.g., biological tissue. FIG. 15 illustrates another embodimentsimilar to that shown in FIG. 14, but wherein a patterned secondfluoropolymer 384 a is provided over the conductive traces 382 a and aportion of the patterned base layer 390 a. In an embodiment, thepatterned second fluoropolymer is provided by exposing and developing(using a fluorinated solvent) a photosensitive fluoropolymer that hascross-linking reactive groups. The patterned second fluoropolymer in thepresent embodiment is designed to stay in place as part of the probedevice. FIG. 16 is a cross-sectional view taken along cut line C-C drawnin FIG. 15. The patterned second fluoropolymer layer is preferablyformed prior to contacting with a resin developing solution, but it mayoptionally be formed afterwards. The electrode pads 383 a revealed bythe patterned second fluoropolymer 384 a may have any suitabledimensions. Photolithographic patterning can enable very high resolutionfeatures having nearly any desired shape. In an embodiment, the revealedelectrode features have an area in a range of 1 to 10,000 μm², oralternatively 25 to 2,500 μm².

One or more of the electrode pads may optionally be further modified.For example, an electrode modifying material, e.g., a conductive polymersuch as PEDOT:PSS, may be provided over the electrode pad. Anillustration is shown in FIG. 17 wherein a modifying material 385 a isprovided over electrode pad 383 a from FIG. 16. In an embodiment,photolithographic patterning techniques mentioned earlier, e.g., etchingor lift-off using the fluoropolymer, may be used to modify the electrodepad with a modifying material. Alternatively, a modifying material maybe ink jetted over the electrode pad and into the well formed by thepatterned second fluoropolymer. Since the electrode pads areaddressable, a modifying material may be provided by electrochemicalmethods, e.g., by electroplating, electropolymerization, electrophoreticdeposition, anodization of the electrode pad surface or the like.Alternatively, the electrode pad may be made of a material thatselectively binds another chemical to form a modifying material layer.For example, a gold electrode pad can bind thiol-containing compounds toform a self-assembled monolayer of modifying material. Depending oncompatibility of the modifying material, its application may be donebefore or after contacting with a resin developing solution. In anembodiment, the patterning of modifying material 385 a is done prior toforming the patterned second fluoropolymer 384 a, and the patternedsecond fluoropolymer may optionally extend over the top edges ofmodifying material 385 a.

In an embodiment, the modifying material 385 a is a conductive polymersuch as PEDOT:PSS and forms part of an organic electrochemicaltransistor or a microelectrode array.

In some embodiments, a patterned material layer provided over the baselayer precursor might not be readily compatible with the resindeveloping solution. When that is the case, a patterned protectivefluoropolymer layer may be provided over the sensitive material. Forexample, although gold may be compatible with a resin developingsolution, an electrode modifying material such as PEDOT:PSS might notbe. An embodiment is shown in FIGS. 18A and 18B. Turning first to FIG.18A, a structure like the one from FIG. 17 is provided, but shown havinga base layer precursor 340 intact (comprising first pattern of exposedradiation-sensitive resin 341 a and second pattern of unexposedradiation-sensitive resin 342), i.e., prior to contact with a resindeveloping agent. FIG. 18A further includes a patterned protectivefluoropolymer layer 386 a applied over modifying material 385 a and aportion of patterned second fluoropolymer 384 a. The protectivefluoropolymer layer 386 a protects the modifying material from the resindeveloping solution and FIG. 18B illustrates the structure after contactwith the resin developing solution. The protective fluoropolymer may beapplied and patterned using methods described earlier when forming thethird pattern of fluoropolymer. In an embodiment, the protectivefluoropolymer layer is formed from a photosensitive fluoropolymer. Theprotective fluoropolymer layer 386 a may later be removed, e.g., bystripping with a fluorinated solvent (not shown in the figure) afterformation of the patterned base layer.

Methods of the present disclosure can be used to readily fabricate anorganic electrochemical transistor (OECT) bioelectronic device, anembodiment of which is shown in FIGS. 20A, 20B and 20C. In FIG. 20A,there is shown a magnified view of a shank tip portion of a patternedbase layer structure 491 that is similar in shape to the patterned baselayer structures of FIG. 13, but the patterned base layer structurecould instead have practically any shape. FIG. 20A shows a patternedbase layer 490, an insulating patterned fluoropolymer 484, gateelectrode 497, and patterned PEDOT:PSS 485 as the channel material. FIG.20B is the same as FIG. 20A except with the patterned fluoropolymer 484removed to illustrate the underlying drain electrode 498, sourceelectrode 499 and conductive traces 482 connecting these electrodes backto an electrical contact portion (as described previously for relatedembodiments). FIG. 20C is a cross-sectional view of the device takenalong cut line D-D drawn in FIG. 20A.

The patterned PEDOT:PSS is provided over a portion of the source anddrain electrodes to make electrical contact, and over the patterned baselayer in a portion extending between the source and drain electrodes.OECT devices are typically immersed in fluid media or biological tissue.The patterned fluoropolymer ensures that the source electrode, drainelectrode and conductive traces are not in direct contact with the fluidor tissue. In the present embodiment, the fluoropolymer also covers anedge portion of the PEDOT:PSS. This can be advantageous in someembodiments (e.g., it may reduce the chances for delamination of thePEDOT:PSS during use), but it is not strictly necessary for thefluoropolymer to cover the PEDOT:PSS edge area. The gate electrode isseparate from the source and drain electrodes and should also not be indirect contact with the patterned PEDOT:PSS. The gate electrode may haveits own, separate PEDOT layer or some other modifying material providedover it. The gate electrode may also comprise different conductivematerial than the drain and source electrodes.

Methods described above can be used to fabricate the shown OECT. In apreferred embodiment when the device is intended for biological tissueuse, the patterned base layer is formed from a photo cross-linking resinhaving a thickness of 10 to 100 μm. The conductive traces and electrodesare patterned by using a lift-off method utilizing a patternedfluoropolymer layer as described previously. In an embodiment, at leasta portion of the conductive traces or one or more of the electrodesinclude a noble metal such as gold, platinum or silver, and mayoptionally include an adhesion layer such as titanium or chromium.Alternatively, the conductive traces or one or more electrodes maycomprise a substantially transparent conductor such as ITO, graphene, ormetal nanowires. The patterned PEDOT:PSS is preferably provided by firstuniformly coating a PEDOT:PSS solution over a substructure having a baselayer precursor, the conductive traces and electrodes, followed byapplying an etch mask (e.g., a patterned fluoropolymer), etching thePEDOT and then removing the etch mask. This method permits uniform andpredictable PEDOT:PSS film thickness which is very important for deviceperformance, especially when preparing multiple OECT devices (over asingle patterned base layer or over multiple patterned base layers).Over this structure, a photosensitive fluoropolymer can be applied andpatterned to substantially cover the conductive traces, and the sourceand drain electrodes, but leaving open at least a portion of the gateelectrode and the PEDOT:PSS channel. In a preferred embodiment, thephotosensitive fluoropolymer is a cross-linking type of fluoropolymer.In an embodiment, the PEDOT:PSS channel covers an area (in a plan viewsuch as FIG. 20A) in a range of about 10 μm² to about 500 μm². In analternative embodiment, the gate electrode is not provided coplanar withthe source and drain and may optionally be provided separately from thepatterned base layer structure entirely (e.g. as a separate Ag orAg/AgCl electrode). In an embodiment, the patterned base layer includesa plurality of independently addressable source and drain electrodes andcorresponding patterned conductive polymers to form a plurality ofOECTs. The patterned base layer may further include other devices inaddition to the OECTs.

Examples of high-performance OECT devices are disclosed in NatureCommunications 4, Article number 2133, Jul. 12, 2013, the contents ofwhich are incorporated herein by reference. However, the methodsdisclosed in the Nature Communications article for making such OECTdevices are not amenable to mass production (e.g., physically peelingoff structures) and may need to be further modified to prepare effectivein vivo devices. The methods of the present disclosure can be used toform uniform arrays of OECT devices (or other devices) having finedimensions, nearly any shape, and on a large scale.

As mentioned above, certain processing steps of the present disclosuremay include the use of a fluorinated solvent. When fluorinated solventsare used, they may be used in some embodiments as mixtures or solutionswith non-fluorinated materials, but typically such mixtures include atleast 50% by volume of a fluorinated solvent, preferably at least 90% byvolume. Depending on the particular material set and solvation needs ofthe process, the fluorinated solvent may be selected from a broad rangeof materials such as chlorofluorocarbons (CFCs),hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs),perfluorocarbons (PFCs), hydrofluoroethers (HFEs), perfluoroethers,perfluoroamines, trifluoromethyl-substituted aromatic solvents,fluoroketones and the like.

Particularly useful fluorinated solvents include those that areperfluorinated or highly fluorinated liquids at room temperature, whichare immiscible with water and most (but not necessarily all) organicsolvents. Among those solvents, hydrofluoroethers (HFEs) are well knownto be highly environmentally friendly, “green” solvents. HFEs, includingsegregated HFEs, are preferred solvents because they are non-flammable,have zero ozone-depletion potential, lower global warming potential thanPFCs and show very low toxicity to humans.

Examples of readily available HFEs and isomeric mixtures of HFEsinclude, but are not limited to, an isomeric mixture of methylnonafluorobutyl ether and methyl nonafluoroisobutyl ether (HFE-7100), anisomeric mixture of ethyl nonafluorobutyl ether and ethylnonafluoroisobutyl ether (HFE-7200 aka Novec™ 7200),3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane(HFE-7500 aka Novec™ 7500),1,1,1,2,3,3-hexafluoro-4-(1,1,2,3,3,3,-hexafluoropropoxy)-pentane(HFE-7600 aka Novec™ 7600), 1-methoxyheptafluoropropane (HFE-7000),1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethylpentane(HFE-7300 aka Novec™ 7300), 1,3-(1,1,2,2-tetrafluoroethoxy)benzene(HFE-978m), 1,2-(1,1,2,2-tetrafluoroethoxy)ethane (HFE-578E),1,1,2,2-tetrafluoroethyl-1H,1H,5H-octafluoropentyl ether (HFE-6512),1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347E),1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458E),2,3,3,4,4-pentafluorotetrahydro-5-methoxy-2,5-bis[1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl]-furan(HFE-7700 aka Novec™ 7700) and1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane-propyl ether (TE6O-C3).

Mixtures of fluorinated solvents may optionally be used, e.g., asdisclosed in U.S. patent application Ser. Nos. 14/260,666 and14/260,705, the entire contents of which are incorporated by referenceherein.

The term “fluoropolymer” herein includes not only high molecular weight,long chain fluorinated materials, but also lower molecular weightoligomers, macrocyclic compounds such as fluorinated calixarenederivatives and other highly fluorinated hydrocarbons having at least 15carbon atoms. In an embodiment, the molecular weight of thefluoropolymer is at least 750. In an embodiment, the fluoropolymer issoluble in one or more fluorinated solvents. Fluoropolymers preferablyhave a total fluorine content by weight in a range of 15% to 75%, oralternatively 30% to 75%, or alternatively 30% to 55%.

When the fluoropolymer is provided as a layer that is not inherentlyphotosensitive (not directly photopatternable, such as described in FIG.5), the fluorine content by weight is preferably in a range of 40% to75%. Some non-limiting coatable examples of such polymers include TeflonAF (copolymer of tetrafluoroethylene with2,2′-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole) and Cytop (a cyclicpolymer formed from F₂C═CFCF₂OCF═CF₂). In an embodiment, thenon-inherently photosensitive fluoropolymer is a copolymer comprising afluorine-containing group (see below for examples) and anon-photosensitive functional group. The non-photosensitive functionalgroup may improve film adhesion, improve coatability, adjust dissolutionrate, absorb light, improve etch resistance and the like. In anembodiment, the non-photosensitive functional group is anon-fluorine-containing aromatic or aliphatic hydrocarbon that mayoptionally be substituted, for example, with oxygen-containing groupssuch as ethers, alcohols, esters, and carboxylic acids.

Photosensitive fluoropolymers can be provided, e.g., by coating aphotosensitive fluoropolymer composition (also referred to herein as afluorinated photopolymer composition) that includes a fluorinatedsolvent, a fluorinated photopolymer material, and optionally additionalmaterials such as sensitizing dyes, photo-acid generator compounds,stabilizers, and the like. In an embodiment, the fluorinatedphotopolymer material includes a copolymer comprising at least twodistinct repeating units, including a first repeating unit having afluorine-containing group and a second repeating unit having asolubility-altering reactive group. In an embodiment using a fluorinatedphotopolymer that is a copolymer, the copolymer has a total fluorinecontent of at least 10%, preferably at least 15%. In an embodiment, thetotal fluorine content is in a range of 15% to 60%, alternatively 30 to60%, or alternatively 35 to 55%. The copolymer is suitably a randomcopolymer, but other copolymer types may be used, e.g., blockcopolymers, alternating copolymers, and periodic copolymers. The term“repeating unit” herein is used broadly herein and simply means thatthere is more than one unit. The term is not intended to convey thatthere is necessarily any particular order or structure with respect tothe other repeating units unless specified otherwise. When a repeatingunit represents a low mole % of the combined repeating units, there maybe only one such unit on a polymer chain. The copolymer may beoptionally blended with one or more other polymers, preferably otherfluorine-containing polymers. The fluoropolymer may optionally bebranched, which may in certain embodiments enable lower fluorinecontent, faster development and stripping rates, or incorporation ofgroups that otherwise may have low solubility in a fluorinated polymer.Non-limiting examples of photosensitive fluoropolymer compositions aredescribed in US Patent Publication 2011/0159252, U.S. patent applicationSer. Nos. 14/113,408, 14/291,692, 14/335,476, U.S. Provisional PatentApplication Nos. 61/990,966, and 61/937,122, the contents of which areincorporated by reference.

In an embodiment, at least one of the specified repeat units is formedvia a post-polymerization reaction. In this embodiment, an intermediatepolymer (a precursor to the desired copolymer) is first prepared, saidintermediate polymer comprising suitably reactive functional groups forforming one of more of the specified repeat units. For example, anintermediate polymer containing pendant carboxylic acid moieties can bereacted with a fluorinated alcohol compound in an esterificationreaction to produce the specified fluorinated repeating unit. Similarly,a precursor polymer containing an alcohol can be reacted with a suitablyderivatized glycidyl moiety to form an acid-catalyzed cross-linkable(epoxy-containing) repeating unit as the solubility-altering reactivegroup. In another example, a polymer containing a suitable leaving groupsuch as primary halide can be reacted with an appropriate compoundbearing a phenol moiety to form the desired repeat unit via anetherification reaction. In addition to simple condensation reactionssuch as esterification and amidation, and simple displacement reactionssuch as etherification, a variety of other covalent-bond formingreactions well-known to practitioners skilled in the art of organicsynthesis can be used to form any of the specified repeat units.Examples include palladium-catalyzed coupling reactions, “click”reactions, addition to multiple bond reactions, Wittig reactions,reactions of acid halides with suitable nucleophiles, and the like.

In an alternative embodiment, the first and second repeating units ofthe copolymer are formed directly by polymerization of two (or more)appropriate monomers, rather than by attachment to an intermediatepolymer. Although many of the embodiments below refer to polymerizablemonomers, analogous structures and ranges are contemplated wherein oneor more of the first and second repeating units are formed by attachmentof the relevant group to an intermediate polymer as described above.

In an embodiment, the fluorinated photopolymer material includes acopolymer formed at least from a first monomer having afluorine-containing group and a second monomer having asolubility-altering reactive group. Additional monomers may optionallybe incorporated into the copolymer. The first monomer is one capable ofbeing copolymerized with the second monomer and has at least onefluorine-containing group. In an embodiment, at least 70% of thefluorine content of the copolymer (by weight) is derived from the firstmonomer. In another embodiment, at least 85% of the fluorine content ofthe copolymer (by weight) is derived from the first monomer.

The first monomer includes a polymerizable group and afluorine-containing group. Some non-limiting examples of usefulpolymerizable groups include acrylates (e.g. acrylate, methacrylate,cyanoacrylate and the like), acrylamides, vinylenes (e.g., styrenes),vinyl ethers and vinyl esters. The fluorine-containing group of thefirst monomer or the first repeating unit is preferably an alkyl or arylgroup that may optionally be further substituted with chemical moietiesother than fluorine, e.g., chlorine, a cyano group, or a substituted orunsubstituted alkyl, alkoxy, alkylthio, aryl, aryloxy, amino, alkanoate,benzoate, alkyl ester, aryl ester, alkanone, sulfonamide or monovalentheterocyclic group, or any other substituent that a skilled worker wouldreadily contemplate that would not adversely affect the performance ofthe fluorinated photopolymer. Throughout this disclosure, unlessotherwise specified, any use of the term alkyl includes straight-chain,branched and cyclo alkyls. In an embodiment, the first monomer does notcontain protic or charged substituents, such as hydroxy, carboxylicacid, sulfonic acid or the like.

In an embodiment, the first monomer has a structure according to formula(1):

In formula (1), R₁ represents a hydrogen atom, a cyano group, a methylgroup or an ethyl group. R₂ represents a fluorine-containing group, inparticular, a substituted or unsubstituted alkyl group having at least 5fluorine atoms, preferably at least 10 fluorine atoms. In an embodiment,the alkyl group is a cyclic or non-cyclic hydrofluorocarbon orhydrofluoroether having at least as many fluorine atoms as carbon atoms.In a preferred embodiment R₂ represents a perfluorinated alkyl or a1H,1H,2H,2H-perfluorinated alkyl having at least 4 carbon atoms. Anexample of the latter is 1H,1H,2H,2H-perfluorooctyl methacrylate(“FOMA”).

A combination of multiple first monomers or first repeating units havingdifferent fluorine-containing groups may be used. The total mole ratioof first monomers relative to all of the monomers of the copolymer maybe in a range of 5 to 80%, or alternatively 10 to 70%, or alternatively20 to 60%.

The second monomer is one capable of being copolymerized with the firstmonomer. The second monomer includes a polymerizable group and asolubility-altering reactive group. Some non-limiting examples of usefulpolymerizable groups include those described for the first monomer.

In an embodiment, the solubility-altering reactive group of the secondmonomer or second repeating unit is an acid-forming precursor group.Upon exposure to light, the acid-forming precursor group generates apolymer-bound acid group, e.g., a carboxylic or sulfonic acid. This candrastically change its solubility relative to the unexposed regionsthereby allowing development of an image with the appropriate solvent.In an embodiment, the developing agent includes a fluorinated solventthat selectively dissolves unexposed areas. In an alternativeembodiment, the developing agent includes a polar solvent thatselectively dissolves the exposed areas. In an embodiment, a carboxylicacid-forming precursor is provided from a monomer in a weight percentagerange of 4 to 40% relative to the copolymer, or alternatively in aweight percentage range of 10 to 30%.

One class of acid-forming precursor groups includes the non-chemicallyamplified type (i.e., non-acid catalyzed). An example of a secondmonomer with such a group is 2-nitrobenzyl methacrylate. Thenon-chemically amplified precursor group may directly absorb light toinitiate de-protection of the acid-forming groups. Alternatively, asensitizing dye may be added to the composition whereby the sensitizingdye absorbs light and forms an excited state capable of directlysensitizing or otherwise initiating the de-protection of acid-formingprecursor groups. The sensitizing dye may be added as a small moleculeor it may be attached or otherwise incorporated as part of thecopolymer. Unlike chemically amplified formulations that rely ongeneration of an acid (see below), non-chemically amplifiedphotopolymers may sometimes be preferred when a photopolymer is used incontact with an acid-sensitive or acid-containing material.

A second class of acid-forming precursor groups includes the chemicallyamplified type. This typically requires addition of a photo-acidgenerator (PAG) to the photopolymer composition, e.g., as a smallmolecule additive to the solution. The PAG may function by directlyabsorbing radiation (e.g. UV light) to cause decomposition of the PAGand release an acid. Alternatively, a sensitizing dye may be added tothe composition whereby the sensitizing dye absorbs radiation and formsan excited state capable of reacting with a PAG to generate an acid. Thesensitizing dye may be added as a small molecule, e.g., as disclosed inU.S. patent application Ser. No. 14/335,476, which is incorporatedherein by reference. The sensitizing dye may be attached to or otherwiseincorporated as part of the copolymer, e.g., as disclosed in U.S. patentapplication Ser. Nos. 14/291,692 and 14/291,767, which are incorporatedherein by reference. In an embodiment, the sensitizing dye (either smallmolecule or attached) is fluorinated. In an embodiment, the sensitizingdye may be provided in a range of 0.5 to 10% by weight relative to thetotal copolymer weight. The photochemically generated acid catalyzes thede-protection of acid-labile protecting groups of the acid-formingprecursor. In some embodiments, chemically amplified photopolymers canbe particularly desirable since they enable the exposing step to beperformed through the application of relatively low energy UV lightexposure. This is advantageous since some active organic materialsuseful in applications to which the present disclosure pertains maydecompose in the presence of UV light, and therefore, reduction of theenergy during this step permits the photopolymer to be exposed withoutcausing significant photolytic damage to underlying active organiclayers. Also, reduced light exposure times improve the manufacturingthroughput of the desired devices.

Examples of acid-forming precursor groups that yield a carboxylic acidinclude, but are not limited to: A) esters capable of forming, orrearranging to, a tertiary cation, e.g., t-butyl ester, t-amyl ester,2-methyl-2-adamantyl ester, 1-ethylcyclopentyl ester, and1-ethylcyclohexyl ester; B) esters of lactone, e.g.,γ-butyrolactone-3-yl, γ-butyrolactone-2-yl, mevalonic lactone,3-methyl-γ-butyrolactone-3-yl, 3-tetrahydrofuranyl, and 3-oxocyclohexyl;C) acetal esters, e.g., 2-tetrahydropyranyl, 2-tetrahydrofuranyl, and2,3-propylenecarbonate-1-yl; D) beta-cyclic ketone esters, E)alpha-cyclic ether esters; and F) MEEMA (methoxy ethoxy ethylmethacrylate) and other esters which are easily hydrolyzable because ofanchimeric assistance. In an embodiment, the second monomer comprises anacrylate-based polymerizable group and a tertiary alkyl esteracid-forming precursor group, e.g., t-butyl methacrylate (“TBMA”) or1-ethylcyclopentyl methacrylate (“ECPMA”).

In an embodiment, the solubility-altering reactive group is anhydroxyl-forming precursor group (also referred to herein as an“alcohol-forming precursor group”). The hydroxyl-forming precursorincludes an acid-labile protecting group and the photopolymercomposition typically includes a PAG compound and operates as a“chemically amplified” type of system. Upon exposure to light, the PAGgenerates an acid (either directly or via a sensitizing dye as describedabove), which in turn, catalyzes the deprotection of thehydroxyl-forming precursor group, thereby forming a polymer-boundalcohol (hydroxyl group). This significantly changes its solubilityrelative to the unexposed regions thereby allowing development of animage with the appropriate solvent (typically fluorinated). In anembodiment, the developing agent includes a fluorinated solvent thatselectively dissolves unexposed areas. In an alternative embodiment, thedeveloping agent includes a polar solvent that selectively dissolves theexposed areas. In an embodiment, an hydroxyl-forming precursor isprovided from a monomer in a weight percentage range of 4 to 40%relative to the copolymer.

In an embodiment, the hydroxyl-forming precursor has a structureaccording to formula (2):

wherein R₅ is a carbon atom that forms part of the second repeating unitor second monomer, and R₁₀ is an acid-labile protecting group.Non-limiting examples of useful acid-labile protecting groups includethose of formula (AL-1), acetal groups of the formula (AL-2), tertiaryalkyl groups of the formula (AL-3) and silane groups of the formula(AL-4).

In formula (AL-1), R₁₁ is a monovalent hydrocarbon group, typically astraight, branched or cyclic alkyl group, of 1 to 20 carbon atoms thatmay optionally be substituted with groups that a skilled worker wouldreadily contemplate would not adversely affect the performance of theprecursor. In an embodiment, R₁₁ may be a tertiary alkyl group. Somerepresentative examples of formula (AL-1) include:

In formula (AL-2), R₁₄ is a monovalent hydrocarbon group, typically astraight, branched or cyclic alkyl group, of 1 to 20 carbon atoms thatmay optionally be substituted. R₁₂ and R₁₃ are independently selectedhydrogen or a monovalent hydrocarbon group, typically a straight,branched or cyclic alkyl group, of 1 to 20 carbon atoms that mayoptionally be substituted. Some representative examples of formula(AL-2) include:

In formula (AL-3), R₁₅, R₁₆, and R₁₇ represent an independently selecteda monovalent hydrocarbon group, typically a straight, branched or cyclicalkyl group, of 1 to 20 carbon atoms that may optionally be substituted.Some representative examples of formula (AL-3) include:

In formula (AL-4), R₁₈, R₁₉ and R₂₀ are independently selectedhydrocarbon groups, typically a straight, branched or cyclic alkylgroup, of 1 to 20 carbon atoms that may optionally be substituted.

The descriptions of the above acid-labile protecting groups for formulae(AL-2), (AL-3) and (AL-4) have been described in the context ofhydroxyl-forming precursors. These same acid-labile protecting groups,when attached instead to a carboxylate group, may also be used to makesome of the acid-forming precursor groups described earlier.

In an embodiment, the solubility-altering reactive group is across-linkable group, e.g., an acid-catalyzed cross-linkable group or aphoto cross-linkable (non-acid catalyzed) group. Photo cross-linkablegroups typically have at least one double bond so that when the groupforms an excited state (either by direct absorption of light or byexcited state transfer from a sensitizing dye), sets of double bondsfrom adjacent polymer chains crosslink. In an embodiment, the photocross-linkable group (not catalyzed) comprises a cinnamate that mayoptionally further include fluorine-containing substituents, asdescribed in U.S. Provisional Application No. 61/937,122, the contentsof which are incorporated herein. Some non-limiting examples ofpolymerizable monomers including such cinnamates are shown below

Compositions comprising such materials may optionally further include asensitizing dye. Some non-limiting examples of useful sensitizing dyesfor cinnamate cross-linking groups include diaryl ketones (e.g.,benzophenones), arylalkyl ketones (e.g., acetophenones), diarylbutadienes, diaryl diketones (e.g. benzils), xanthones, thioxanthones,naphthalenes, anthracenes, benzanthrone, phenanthrenes, crysens,anthrones, 5-nitroacenapthene, 4-nitroaniline, 3-nitrofluorene,4-nitromethylaniline, 4-nitrobiphenyl, picramide,4-nitro-2,6-dichlorodimethylaniline, Michler's ketone,N-acyl-4-nitro-1-naphthylamine.

Examples of acid-catalyzed cross-linkable groups include, but are notlimited to, cyclic ether groups and vinyloxy groups. In an embodiment,the cyclic ether is an epoxide or an oxetane. The photopolymercomposition including an acid-catalyzed cross-linkable group typicallyincludes a PAG compound and operates as a “chemically amplified” type ofsystem in a manner described above. Upon exposure to light, the PAGgenerates an acid (either directly or via a sensitizing dye as describedabove), which in turn, catalyzes the cross-linking of the acid-catalyzedcross-linkable groups. This significantly changes its solubilityrelative to the unexposed regions thereby allowing development of animage with the appropriate fluorinated solvent. Usually, cross-linkingreduces solubility. In an embodiment, the developing agent includes afluorinated solvent that selectively dissolves unexposed areas. In anembodiment, a cross-linkable group is provided from a monomer in aweight percentage range of 4 to 40% relative to the copolymer.

Some non-limiting examples of some acid-catalyzed cross-linkable groupsinclude the following wherein (*) refers to an attachment site to thepolymer or the polymerizable group of a monomer:

In an embodiment, the solubility-altering reactive groups are ones that,when the photopolymer composition or layer is exposed to light, undergoa bond-breaking reaction to form a material with higher solubility influorinated solvents. For example, the solubility-altering reactivegroups could be cross-linked and the links are broken upon exposure tolight thereby forming lower molecular weight materials. In thisembodiment, a fluorinated solvent may be selected to selectively removeexposed areas, thereby acting as a positive photopolymer system.

A combination of multiple second monomers or second repeating unitshaving different solubility-altering reactive groups may be used. Forexample, a fluorinated photopolymer may comprise both acid-forming andan alcohol-forming precursor groups.

The copolymer may optionally include additional repeating units havingother functional groups or purposes. For example, the copolymer mayoptionally include a repeating unit that adjusts some photopolymer orfilm property (e.g., solubility, Tg, light absorption, sensitizationefficiency, adhesion, surface wetting, etch resistance, dielectricconstant, branching and the like).

Many useful PAG compounds exist that may be added to a photopolymercomposition. In the presence of proper exposure and sensitization, thisphoto-acid generator will liberate an acid, which will react with thesecond monomer portion of the fluorinated photopolymer material totransform it into a less soluble form with respect to fluorinatedsolvents. The PAG needs to have some solubility in the coating solvent.The amount of PAG required depends upon the particular system, butgenerally, will be in a range of 0.1 to 6% by weight relative to thecopolymer. In an embodiment, the amount of PAG is in a range of 0.1 to2% relative to the copolymer. Fluorinated PAGs are generally preferredand non-ionic PAGs are particularly useful. Some useful examples of PAGcompounds include2-[2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)-pentyl]-fluorene(ONPF) and2-[2,2,3,3,4,4,4-heptafluoro-1-(nonafluorobutylsulfonyloxyimino)-butyl]-fluorene(HNBF). Other non-ionic PAGS include: norbornene-based non-ionic PAGssuch as N-hydroxy-5-norbornene-2,3-dicarboximideperfluorooctanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboximideperfluorobutanesulfonate, and N-hydroxy-5-norbornene-2,3-dicarboximidetrifluoromethanesulfonate; and naphthalene-based non-ionic PAGs such asN-hydroxynaphthalimide perfluorooctanesulfonate, N-hydroxynaphthalimideperfluorobutanesulfonate and N-hydroxynaphthalimidetrifluoromethanesulfonate. Suitable PAGs are not limited to thosespecifically mentioned above and some ionic PAGs can work, too.Combinations of two or more PAGs may be used as well.

Representative Embodiments

Below are some non-limiting, representative embodiments of the presentdisclosure.

-   -   1. A method of making a structure having a patterned base layer,        comprising the steps of:    -   providing a layer of a radiation-sensitive resin;    -   exposing the layer of radiation-sensitive resin to patterned        radiation to form a base layer precursor having a first pattern        of exposed radiation-sensitive resin and a second pattern of        unexposed radiation-sensitive resin;    -   providing a layer of fluoropolymer in a third pattern over the        base layer precursor to form a first intermediate structure;    -   treating the first intermediate structure to form a second        intermediate structure; and    -   selectively removing either the first or second pattern of resin        by contacting the second intermediate structure with a resin        developing agent, thereby forming the patterned base layer.    -   2. The method according to embodiment 1 wherein the layer of        radiation-sensitive resin is provided over a carrier substrate.    -   3. The method according to embodiment 1 or 2 wherein the        structure includes at least one electronic or optical feature        that is provided over the patterned base layer.    -   4. The method according to embodiment 3 wherein the electronic        or optical feature forms at least a portion of a transistor, a        capacitor, a light-emitting device, a touch screen, a        photovoltaic device, a display device, a chemical sensor, a        light sensor, a bio-sensor, a bio-stimulator, a bioelectronic        ion pump, an electrochemical cell, an organic electrochemical        transistor, a light guide, a lens, a reflector, a color filter,        a piezo device, a MEMS device or combinations thereof    -   5. The method according to any of embodiments 1-4 wherein the        patterned base layer has a Young's modulus of 1 kPa or higher.    -   6. The method according to any of embodiments 1-5 wherein the        patterned base layer has a Tg of 100° C. or higher.    -   7. The method according to embodiment 2 further including        removal of the second intermediate structure or the patterned        base layer from the carrier support.    -   8. The method according to embodiment 7 further comprising        providing a release layer between the carrier support and the        layer of radiation-sensitive resin, wherein the release layer        promotes removal of the second intermediate structure or the        patterned base layer.    -   9. The method according to any of embodiments 2-8 wherein the        structure having a patterned base layer is one of a plurality of        concurrently formed structures, each having a patterned base        layer.    -   10. The method according to embodiment 9 wherein at least one of        the plurality of structures has a patterned base layer in a        first shape and at least one other of the plurality of        structures has a patterned base layer in a second shape        different from the first shape.    -   11. The method according to any of embodiments 7-10 further        comprising transferring the structure to a secondary substrate.    -   12. The method according to any of embodiments 1-8 wherein the        patterned base layer has an elongated shape and the structure        has sufficient mechanical strength to allow insertion into        biological tissue.    -   13. The method according to any of embodiments 1-12 wherein the        patterned base layer has a thickness in a range of 10 to 100 μm.    -   14. The method according to any of embodiments 1-13 wherein the        patterned radiation causes cross-linking or polymerization in        the first pattern of exposed radiation-sensitive resin, whereby        contact with the resin developing agent selectively removes the        second pattern of unexposed radiation-sensitive resin.    -   15. The method according to embodiment 14 wherein the        radiation-sensitive resin comprises an epoxy- or acrylate-based        cross linkable group.    -   16. The method according to any of embodiments 1-15 wherein the        third pattern of fluoropolymer is provided by:    -   i) applying a composition comprising a photosensitive        fluoropolymer material and a first fluorinated solvent to form a        layer of photosensitive fluoropolymer;    -   ii) exposing the photosensitive fluoropolymer to radiation in a        pattern corresponding to the third pattern, thereby forming an        exposed layer of photosensitive fluoropolymer; and    -   iii) contacting the exposed layer of photosensitive        fluoropolymer with a photosensitive fluoropolymer developing        agent comprising at least 50% by volume of a second fluorinated        solvent to selectively remove unexposed areas of the        photosensitive fluoropolymer.    -   17. The method according to embodiment 16 wherein the        photosensitive fluoropolymer material comprises a copolymer        having at least two distinct repeating units, including a first        repeating unit having a fluorine-containing group and a second        repeating unit having a solubility-altering reactive group.    -   18. The method according to embodiment 17 wherein the        solubility-altering reactive group is a carboxylic or sulfonic        acid-forming precursor group, an alcohol-forming precursor group        or a cross-linking group.    -   19. The method according to embodiments 16-18, wherein the first        or second fluorinated solvent, or both, includes a        hydrofluoroether.    -   20. The method according to any of embodiments 1-19 wherein the        fluorine content of the fluoropolymer is in a range of 15-60% by        weight.    -   21. The method according to any of embodiments 1-15 wherein the        third pattern of fluoropolymer is provided by:    -   a) applying a layer of non-patterned fluoropolymer over the base        layer precursor, wherein the fluoropolymer is soluble in a        fluorinated solvent;    -   b) providing over the layer of non-patterned fluorinated polymer        a layer of a second polymer in a pattern corresponding to the        third pattern to form a partially patterned bilayer polymer        structure, wherein the second polymer is substantially insoluble        in the fluorinated solvent; and    -   c) contacting the partially patterned bilayer polymer structure        with the fluorinated solvent to selectively remove the        fluoropolymer in areas not covered by the second polymer.    -   22. The method according to embodiment 21 wherein the second        polymer is a photoresist having a total fluorine content by        weight of less than 15% and the fluoropolymer has a total        fluorine content by weight of greater than 40%.    -   23. The method according to embodiments 21 or 22 wherein the        fluorinated solvent includes a hydrofluoroether, a        hydrofluorocarbon or a perfluorinated compound.    -   24. The method according to any of embodiments 1-23 wherein the        treating includes depositing a first material layer over the        first intermediate structure.    -   25. The method according to embodiment 24 wherein the        fluoropolymer is removed, thereby removing first material over        the third pattern of fluoropolymer and forming a patterned first        material layer in areas other than the third pattern.    -   26. The method according to embodiment 24 or 25 wherein the        first material layer forms at least a portion of an electronic        or optical feature.    -   27. The method according to embodiment 26 wherein the first        material is a metal conductor.    -   28. The method according to embodiment 26 wherein the first        material is an organic conductor, an organic semiconductor or an        organic light-emitting material.    -   29. The method according to any of embodiments 1-28 further        comprising providing a second material layer over the radiation        sensitive resin and prior to providing the layer of        fluoropolymer in a third pattern, and wherein the treating        comprises etching the second material layer using the third        pattern of fluoropolymer as an etch mask.    -   30. The method according to embodiment 29 wherein the second        material is an organic conductor, an organic semiconductor or an        organic light-emitting material.    -   31. The method according to embodiments 29 or 30 further        comprising removal of the third pattern of fluoropolymer to form        an uncovered patterned second material layer in areas        corresponding to the third pattern.    -   32. The method according to any one of embodiments 1-31 wherein        the first pattern of exposed radiation-sensitive resin has a        first Tg and the second pattern of unexposed radiation-sensitive        resin has a second Tg, and wherein the steps of forming the        first and second intermediate structures do not subject the base        layer precursor to temperatures that exceed either the first Tg        or the second Tg.    -   33. An organic electrochemical transistor device comprising:    -   a patterned base layer comprising a photochemically cross linked        resin;    -   a source electrode separated from a drain electrode provided        over the patterned base layer;    -   a patterned conductive polymer provided over at least a portion        of the source and drain electrodes and over the patterned base        layer in a portion extending between the source and drain        electrodes; and    -   an insulating patterned fluoropolymer layer provided over the        source and drain electrodes and further includes an opening over        the portion of conductive polymer extending between the source        and drain electrodes.    -   34. The device of embodiment 33 further comprising a gate        electrode provided over the patterned base layer but separate        from the patterned conductive polymer.    -   35. The device of embodiment 33 or 34 further comprising        conductive traces extending from the electrodes to an electrical        contact portion of the patterned base layer, wherein the        insulating patterned fluoropolymer layer covers the conductive        traces in regions intended for immersion into a fluid or        biological tissue sample.    -   36. The device according to any of embodiments 33-35 wherein        patterned fluoropolymer layer is a photochemically cross-linked        fluoropolymer.    -   37. The device according to any of embodiments 33-36 wherein the        photochemically cross-linked resin has a thickness in a range of        10 to 100 μm.    -   38. The device according to any of embodiments 33-37 wherein the        opening in the patterned fluoropolymer has an area in a range of        10 μm² to 500 μm².    -   39. The device according to any of embodiments 33-38 wherein the        organic electrochemical transistor device comprises a plurality        of independently addressable source and drain electrodes and        corresponding patterned conductive polymers.

EXAMPLES Example 1

A silicon wafer having an oxide layer was cleaned in acetone and IPAwith sonication and dried. A 10% solution of Decon® 90 (comprisinganionic and non-ionic surfactants) was spin applied and dried to form avery thin release layer. SU8 2050 was applied and spin coated up to 3500rpm, baked first at 65° C. for 3 min then 95° C. for 9 min and slowlycooled to prevent thermal shock and cracking. The SU8 was about 50 μmthick. Using a shadow mask and a SUSS MicroTec mask aligner, the waferwas pattern exposed to i-line radiation with a total dose of 504 mJ/cm².The exposed image was similar in shape to that of part 391 a in FIG. 13.The exposed film was given a post exposure bake at 65° C. for 2 min then95° C. for 6 min, but not developed.

Over this structure, OSCoR 4000 photoresist (from Orthogonal, Inc.) wascoated at 1500 rpm and soft baked at 90 C for 1 min. OSCoR 4000 is aphotosensitive fluorinated photopolymer provided in a hydrofluoroethersolvent along with a fluorinated non-ionic PAG. The fluorine content ofthe photosensitive fluoropolymer was about 42% by weight and the polymerincluded a carboxylic acid-forming precursor group. The film thicknesswas about 0.9 μm. Using a shadow mask and a SUSS MicroTec mask aligner,the wafer was pattern exposed to i-line radiation with a total dose of80 mJ/cm² and given a post exposure bake of 90° C. for 1 min. This wasfollowed by development using three (3) 30 sec puddles of OrthogonalDeveloper 103 (comprises a hydrofluoroether solvent that is differentfrom the OSCoR 4000 coating solvent), each followed by spin dry step.This formed a set of open lines and pad areas of various dimensions (inthis case, all >20 μm).

Following development of the OSCoR 4000, the structure was given agentle plasma etch (100 W, 50 sccm O₂), followed by deposition of 10 nmCr and then 100 nm Au. The structure was immersed in OSCoR Stripper 700(comprising another hydrofluoroether) overnight and the photoresist andoverlying metal layers were lifted off leaving patterned metal over thebase layer precursor.

Next the SU8 was developed using a commercial PGMEA-based SU8 developerfor 10 mins followed by a short DI water rinse which released thepatterned base layer structure from the Si wafer.

Comparison 1

The steps were followed initially as in Example 1, but in place of OSCoR4000, commercially available nLOF 2070 (AZ Electronic Materials)photoresist was used. Coating of the nLOF 2070 caused prematuredissolution of the unexposed SU8 resulting in massive failure of thepatterning attempt at this point. Another conventional photoresistsystem in the art uses a lift-off method involving bilayer of LoR5A (apolydimethylgutarimide from MicroChem) and overlying conventionalphotoresist. However, it was found that the LoR5A coating and lift-offsolvent, NMP, rapidly dissolves unexposed SU8 and so this system is alsonot suitable for imaging.

Example 2

A 1.3 μm film of SU8 was prepared on a 2 cm×2 cm silicon wafer chip byspin coating SU8 3025 (diluted with cyclohexanone) at 1000 rpm, followedby a 1 min/90° C. post apply bake. The chip had four quadrants, Q1, Q2,Q3 and Q4 as shown in FIG. 21 and the SU8 was coated over all fourquadrants. Next, half of the chip (quadrants Q1 and Q2) was exposed on aPluvex 1410 UV exposure unit to a dose of 492 mJ/cm² as measured at 365nm, followed by a 2 min PEB at 90° C.

Next a saturated solution of an organic semiconductor material,TIPS-pentacene (6,13-bis(triisopropylsilylethynyl)pentacene) in HMDSO(hexamethyldisiloxane) solvent was spin coated at 300 rpm and dried 10sec at 90° C. to form a bluish, polycrystalline film over the SU8. OSCoR4000 photoresist from Orthogonal, Inc. was spin coated at 1000 rpm andbaked 30 sec at 90° C. to form a 1.3 μm film. Half of thisphotosensitive fluoropolymer was exposed (quadrants Q2 and Q3) to 200mJ/cm², followed by a 1 min PEB at 90° C. The exposed fluoropolymer wasdeveloped with Orthogonal Developer 103 (includes a hydrofluoroethersolvent) using three (3) 30 sec puddles, each followed by a spin drystep. The TIPS-pentacene was still clearly present in all areas and“uncovered” in quadrants Q1 and Q4. The uncovered TIPS-pentacene was“wet” etched by applying three (3) 15 sec puddles of HMDSO to the waferfollowed by spin drying, thereby leaving TIPS-pentacene only underneaththe OSCoR 4000 resist in quadrants Q2 and Q3.

Next, the SU8 was developed by applying two (2) 15 sec puddles of PGMEAsolvent (which lifted off OSCoR 4000 in quadrant Q3 along withdissolving TIPS pentacene in Q3). The OSCoR 4000 was subsequentlystripped using Orthogonal Stripper 700 (includes a hydrofluoroethersolvent) thereby forming a patterned base layer of SU8 having a patterncorresponding to quadrants Q1 and Q2, and deposited thereon, a layer ofactive organic material (TIPS-pentacene) in a pattern corresponding toquadrant Q2. Rather than relying on lift off in quadrant Q3, in analternative embodiment, the OSCoR 4000 could have instead been imagedonly in quadrant Q2.

Comparison 2

The steps were followed initially as in Example 2, but in place of OSCoR4000, commercially available nLOF 2020 (AZ Electronics Materials)photoresist was used. Coating of the nLOF caused dissolution of theTIPS-pentacene and unexposed SU8 thereby resulting in massive failure ofthe patterning attempt.

Example 3

A film of SU8 (2050) was spin coated and dried in a manner similar tothat described Example 1 except that the substrate was a glass slide,2.5 cm×7.5 cm. The glass slide had four quadrants similar to thosedescribed in Example 2 and FIG. 21, except the sample was rectangularrather than square. Half of the SU8 film (quadrants Q1 and Q2) wasexposed to i-line UV radiation with a total dose of 550 mJ/cm². Theexposed film was given a post exposure bake at 65° C. for 2 min then 95°C. for 6 min, but not developed. The SU8 surface was cleaned in a gentleO₂ plasma (100 W, 1 min, 50 sccm of O₂). A thin film of about 100 nmPEDOT:PSS was formed by spin coating (up to 4000 rpm, 40 sec) a 1%aqueous solution over the SU8, and given a post-apply bake of 90° C. for1 min.

Over this structure, OSCoR 3313 photoresist (from Orthogonal, Inc.) wascoated at 1000 rpm and soft baked at 90° C. for 20 sec. OSCoR 3313 is aphotosensitive fluorinated photopolymer provided in a hydrofluoroethersolvent along with a fluorinated non-ionic PAG. The fluorine content ofthe photosensitive fluoropolymer was about 41% by weight and the polymerincluded both a carboxylic acid-forming precursor group and analcohol-forming precursor group. The film thickness was about 1.3 μm.Next, a portion of quadrant Q1 was exposed to i-line radiation with atotal dose of about 72 mJ/cm² and given a post exposure bake of 90° C.for 20 sec. This was followed by development using two (2) 1 min puddlesand one (1) 30 sec puddle of Orthogonal Developer 100 (comprises ahydrofluoroether solvent that is different from the OSCoR 3313 coatingsolvent), each followed by spin dry step.

Next, PEDOT:PSS in areas not covered by the patterned OSCoR 3313 wereplasma etched (160 W, 80 sec, 50 sccm O₂/5 sccm CHF₃). PEDOT:PSS in theportion of quadrant Q1 was protected by the overlying patterned OSCoR3313. The OSCoR 3313 was removed using Orthogonal Stripper 700 (1 min)followed by a spin dry step. Finally, the SU8 was developed using acommercial PGMEA-based SU8 developer for 15 mins, thereby forming apatterned base layer structure having an SU8 base layer in a patterncorresponding to quadrants Q1 and Q2 and having thereon a pattern ofPEDOT:PSS in a portion of quadrant Q1. In an alternative embodiment, theSU8 could have instead been developed prior to stripping the OSCoR 3313.

The invention has been described in detail with particular reference tocertain embodiments thereof, but it will be understood that variations,combinations, and modifications can be effected by a person of ordinaryskill in the art within the spirit and scope of the invention.

LIST OF REFERENCE NUMBERS USED IN THE DRAWINGS

-   2 provide layer of radiation-sensitive resin step-   4 form base layer precursor step-   6 form first intermediate structure step-   8 form second intermediate structure step-   9 form patterned base layer step-   20 radiation-sensitive resin-   22 carrier substrate-   24 release layer-   40 base layer precursor-   41 first pattern of exposed radiation-sensitive resin-   42 second pattern of unexposed radiation-sensitive resin-   45 photomask-   46 radiation-   60 photosensitive fluoropolymer-   61 radiation-   62 photomask-   63 exposed layer of photosensitive fluoropolymer-   64 pattern of exposed photosensitive fluoropolymer-   65 pattern of unexposed photosensitive fluoropolymer-   66 third pattern of fluoropolymer-   67 first intermediate structure-   80 material layer-   81 patterned material layer-   82 second intermediate structure-   83 second intermediate structure-   90 patterned base layer-   91 patterned base layer structure-   92 patterned base layer-   93 patterned base layer structure-   160 non-patterned fluoropolymer-   161 photosensitive second polymer-   163 exposed layer of photosensitive second polymer-   164 pattern of exposed photosensitive second polymer-   165 pattern of unexposed photosensitive second polymer-   166 patterned layer of second polymer-   167 first intermediate structure-   168 partially patterned bilayer structure-   200 secondary substrate-   201 adhesion promoting layer-   210 pressure-   220 secondary substrate structure-   260 photosensitive fluoropolymer-   261 radiation-   262 photomask-   263 exposed layer of photosensitive fluoropolymer-   264 pattern of exposed photosensitive fluoropolymer-   265 pattern of unexposed photosensitive fluoropolymer-   266 third pattern of fluoropolymer-   267 first intermediate structure-   280 material layer-   281 patterned material layer-   282 second intermediate structure-   290 patterned base layer-   291 patterned base layer structure-   300 patterned base layer structure array-   322 carrier substrate-   324 release layer-   340 base layer precursor-   341 first pattern of exposed radiation-sensitive resin-   342 second pattern of unexposed radiation-sensitive resin-   381 electrical contact pads-   382 conductive traces-   383 electrode pad-   384 patterned second fluoropolymer-   385 modifying material-   386 protective fluoropolymer layer-   390 patterned base layer-   391 patterned base layer structure-   395 electrical contact portion-   398 shank portion-   482 conductive traces-   484 patterned fluoropolymer-   485 patterned PEDOT:PSS-   490 patterned base layer-   491 patterned base layer structure-   497 gate electrode-   498 source electrode-   499 drain electrode-   Q1 first quadrant of Si chip-   Q2 second quadrant of Si chip-   Q3 third quadrant of Si chip-   Q4 fourth quadrant of Si chip

The invention claimed is:
 1. An organic electrochemical transistordevice comprising: a patterned base layer comprising a cross linkedresin; a source electrode separated from a drain electrode provided overthe patterned base layer; a patterned conductive polymer provided overat least a portion of the source and drain electrodes and over thepatterned base layer in a portion extending between the source and drainelectrodes; and an insulating patterned fluoropolymer layer providedover the source and drain electrodes and further includes an openingover the portion of conductive polymer extending between the source anddrain electrodes.
 2. The device of claim 1 further comprising a gateelectrode provided over the patterned base layer but separate from thepatterned conductive polymer.
 3. The device of claim 1 furthercomprising conductive traces extending from the electrodes to anelectrical contact portion of the patterned base layer, wherein theinsulating patterned fluoropolymer layer covers the conductive traces inregions intended for immersion into a fluid or biological tissue sample.4. The device according to claim 1 wherein the patterned fluoropolymerlayer is a photochemically cross-linked fluoropolymer.
 5. The deviceaccording to claim 1 wherein the cross-linked resin has a thickness in arange of 10 to 100 μm.
 6. The device according to claim 1 wherein theopening in the patterned fluoropolymer has an area in a range of 10 μm²to 500 μm².
 7. The device according to claim 1 wherein the organicelectrochemical transistor device comprises a plurality of independentlyaddressable source and drain electrodes and corresponding patternedconductive polymers.
 8. The device according to claim 1 wherein theorganic electrochemical transistor device comprises a plurality ofindependently addressable source and drain electrodes and correspondingpatterned conductive polymers.
 9. An organic electrochemical transistordevice comprising: a source electrode separated from a drain electrodeprovided over a base layer; a patterned conductive polymer provided overat least a portion of the source and drain electrodes and over the baselayer in a portion extending between the source and drain electrodes;and an insulating patterned fluoropolymer layer provided over the sourceand drain electrodes and over a first portion of the conductive polymer,the fluoropolymer layer having an opening over a second portion ofconductive polymer extending between the source and drain electrodes.10. The device of claim 9 further comprising a gate electrode providedover the base layer but separate from the patterned conductive polymer.11. The device of claim 9 further comprising conductive traces extendingfrom the electrodes to an electrical contact portion of the base layer,wherein the insulating patterned fluoropolymer layer covers theconductive traces in regions intended for immersion into a fluid orbiological tissue sample.
 12. The device according to claim 9 whereinthe patterned fluoropolymer layer is a photochemically cross-linkedfluoropolymer.
 13. The device according to claim 9 wherein the baselayer has a thickness in a range of 10 to 100 μm.
 14. The deviceaccording to claim 9 wherein the opening in the patterned fluoropolymerhas an area in a range of 10 μm² to 500 μm².